Retractor for a seat belt

Abstract

A belt retractor for a seat belt includes a belt reel, an eccentric disc connected to the belt reel, a cam disc driven by the eccentric disc, and a blocking pawl. The blocking pawl, in a blocking position, blocks a toothed ratchet wheel, and, in a release position, leaves the toothed ratchet wheel unaffected. The blocking pawl may be switched from the release position into the blocking position and conversely from the blocking position into the release position with the cam disc. For the belt retractor to be independent of tolerances, provision is made for the cam disc to have an engaging cam for engaging the blocking position of the blocking pawl and a disengaging cam for engaging the release position of the blocking pawl.

1. A retractor for a seat belt comprising:
 a belt reel and an eccentric disc fixed to the belt reel such that the eccentric disc rotates with the belt reel; 
 a cam disc driven directly by the eccentric disc and including an engaging cam and a disengaging cam arranged separately from the engaging cam; 
 a toothed ratchet wheel configured to rotate at the same time as the belt reel in a pull-out direction of the seat belt; and 
 a blocking pawl which, in a blocking position, blocks rotation of the toothed ratchet wheel and which, in a release position, leaves the toothed ratchet wheel unaffected, 
 wherein the blocking pawl is configured to be switched from the release position into the blocking position and vice versa by the cam disc, 
 wherein the engaging cam of the cam disc is configured to engage the blocking pawl to move it to the blocking position, and 
 wherein the disengaging cam of the cam disc is configured to engage the blocking pawl to move it to the release position. 
 
   
   
     2. The retractor of  claim 1 , wherein the blocking pawl comprises an engaging lever which interacts exclusively with the engaging cam and a disengaging lever which interacts exclusively with the disengaging cam. 
   
   
     3. The retractor of  claim 2 , wherein the engaging lever is configured so that the engaging lever cannot be touched by the disengaging cam, deflected by the disengaging cam, or a combination of touched and deflected by the disengaging cam, and
 wherein the disengaging lever of the blocking pawl is dimensioned and arranged in such a manner that the disengaging lever cannot be touched by the engaging cam, deflected by the engaging cam, or a combination of touched and deflected by the engaging cam. 
 
   
   
     4. The retractor of  claim 3 , wherein one of the two cams of the cam disc has an active switching surface which is at a greater distance from a center point of the cam disc than an active switching surface of the other cam of the cam disc. 
   
   
     5. The retractor of  claim 3 , wherein the disengaging cam and the engaging cam each have a height above a basic flat surface of the cam disc. 
   
   
     6. The retractor of  claim 5 , wherein the height of one of the two cams of the cam disc is higher than the height of the other of the two cams of the cam disc. 
   
   
     7. The retractor of  claim 1 , wherein the blocking pawl is mounted rotatably about an axis of rotation. 
   
   
     8. The retractor of  claim 7 , wherein the belt retractor further comprises a housing, and wherein the axis of rotation is arranged on the housing of the belt retractor. 
   
   
     9. The retractor of  claim 1 , wherein the blocking pawl is locked in the blocking position or in the release position by a spring. 
   
   
     10. The retractor of  claim 9 , wherein the spring includes a metal spring. 
   
   
     11. The retractor of  claim 9 , wherein the spring includes a plastic spring. 
   
   
     12. The retractor of  claim 11 , wherein the belt retractor further comprises a housing, and wherein the spring includes a plastic element located on the housing of the retractor. 
   
   
     13. The retractor of  claim 9 , wherein the spring has two recesses, wherein one of the recesses fixes a latching lug of the blocking pawl in the blocking position, and wherein the other recess fixes the latching lug of the blocking pawl in the release position. 
   
   
     14. The retractor of  claim 9 , wherein when the blocking pawl is switched from the blocking position into the release position and conversely from the release position into the blocking position, the spring has to overcome a dead-center position. 
   
   
     15. The retractor of  claim 1 , wherein the belt retractor further comprises a housing,
 wherein the cam disc has an outer, toothed edge comprising teeth, wherein the teeth of the outer, toothed edge are surrounded by an inner toothed ring which is fixed on the housing, wherein the outer toothed edge is of larger diameter than the inner toothed ring and has complementary teeth, 
 wherein the cam disc is in meshing engagement with the inner toothed ring over a limited circumferential region, and 
 wherein teeth of the outer edge and inner ring are arranged at such a radial distance diametrically opposite each other that the cam disc rolls along the inner toothed ring when the belt reel of the belt retractor is rotated. 
 
   
   
     16. The retractor of  claim 15 , wherein the eccentric disc, the inner toothed ring, and the cam disc form a step-down gear. 
   
   
     17. The retractor of  claim 16 , wherein the cam disc has N teeth and the inner toothed ring has N +1 teeth. 
   
   
     18. The retractor of  claim 17 , wherein N =26. 
   
   
     19. The retractor of  claim 15 , wherein the eccentric disc, the inner toothed ring, and the cam disc form a wobble gear. 
   
   
     20. A retractor for a seat belt comprising:
 a belt reel; 
 an eccentric disc connected to the belt reel; 
 a cam disc driven by the eccentric disc and including an engaging cam and a disengaging cam; and 
 a blocking pawl configured to be placed in a blocking position and a release position so that when the blocking pawl is in the blocking position the blocking pawl blocks a toothed ratchet wheel which rotates at the same time as the belt reel in a belt pull-out direction of rotation of the seat belt, and when the blocking pawl is in the release position the rotation of the toothed ratchet wheel is unaffected, 
 wherein the blocking pawl is configured to be switched from the release position into the blocking position and vice versa by the cam disc, 
 wherein the engaging cam of the cam disc is configured to engage the blocking pawl to move it to the blocking position, and wherein the disengaging cam of the cam disc is configured to engage the blocking pawl to move it to the release position. 
 
   
   
     21. The retractor of  claim 20 , wherein the blocking pawl comprises an engaging lever which interacts exclusively with the engaging cam and a disengaging lever which interacts exclusively with the disengaging cam. 
   
   
     22. The retractor of  claim 21 , wherein the engaging lever is dimensioned and arranged in such a manner that the engaging lever cannot be touched by the disengaging cam, deflected by the disengaging cam, or a combination of touched and deflected by the disengaging cam, and
 wherein the disengaging lever of the blocking pawl is dimensioned and arranged in such a manner that the disengaging lever cannot be touched by the engaging cam, deflected by the engaging cam, or a combination of touched and deflected by the engaging cam. 
 
   
   
     23. The retractor of  claim 20 , wherein the blocking pawl is locked in the blocking position or in the release position by a spring. 
   
   
     24. The retractor of  claim 23 , wherein the spring has two recesses, wherein one of the recesses fixes a latching lug of the blocking pawl in the blocking position, and wherein the other recess fixes the latching lug of the blocking pawl in the release position.